This can be caused buy answering an inbound call, playing something in early media such as artificial ringback then bridging to another endpoint.  While it's ringing, FS is generating timestamps, once it's bridged we pass through the timestamps from the far end to allow jitter to remain visible and preserve the far end timestamps.  As pointed out above, there is a parameter to force the timestamps to a new value which is a bad idea if you can help it because then you lock any jitter into place by putting correctly sequenced timestamps on it.  Some sonus switches reset their DSP when they see the timestamps change and the mark bit set which causes a pause in the audio.


On Wed, Jul 21, 2010 at 11:52 AM, Steven Ayre <steveayre@gmail.com> wrote:
I know, but it's worth checking in case he isn't on the default config. ;)


On 21 July 2010 16:54, David Ponzone <david.ponzone@gmail.com> wrote:
Steven,

sure, and in the default config, rtp-rewrite-timestamps is commented out and false by default.

David Ponzone  Direction Technique
tel:      01 74 03 18 97
gsm:   06 66 98 76 34

Service Client IPeva
tel:      0811 46 26 26

Ce message et toutes les pièces jointes sont confidentiels et établis à l'intention exclusive de ses destinataires. Toute utilisation ou diffusion non autorisée est interdite. Tout message électronique est susceptible d'altération. IPeva décline toute responsabilité au titre de ce message s'il a été altéré, déformé ou falsifié. Si vous n'êtes pas destinataire de ce message, merci de le détruire immédiatement et d'avertir l'expéditeur.




Le 21/07/2010 à 17:44, Steven Ayre a écrit :

That's not quite true - if it depends on the value in the sip profile of:
<param name="rtp-rewrite-timestamps" value="true"/>

Sonus is known to have timestamp problems. Is there a Sonus gateway anywhere in the media path?

-Steve


On 21 July 2010 15:51, David Ponzone <david.ponzone@gmail.com> wrote:
Neil,

as far as I know, by default, FS is transparent for timestamps.
It writes in outbound RTP the exact timestamp that it received in inbound RTP.
So you should perhaps have a look at the sending endpoint ?

David Ponzone  Direction Technique
tel:      01 74 03 18 97
gsm:   06 66 98 76 34

Service Client IPeva
tel:      0811 46 26 26

Ce message et toutes les pièces jointes sont confidentiels et établis à l'intention exclusive de ses destinataires. Toute utilisation ou diffusion non autorisée est interdite. Tout message électronique est susceptible d'altération. IPeva décline toute responsabilité au titre de ce message s'il a été altéré, déformé ou falsifié. Si vous n'êtes pas destinataire de ce message, merci de le détruire immédiatement et d'avertir l'expéditeur.




Le 21/07/2010 à 16:36, Neil Burgess a écrit :

Hi,
 
We are capturing packets for call quality monitoring purposes, and as part of the capture, we are grabbing the outbound packets from FreeSwitch. We are noticing what appears to be an odd behaviour in the RTP sequence timing where suddenly the timing will jump from the regular 160 increments to a number in the 10’s of millions! See packet 38 below. Now I have no idea as to whether such a timing change is OK in RTP, and although the actual RTP stream does not appear to be affected, I do see that Wireshark believes there is a massive amount of jitter on the line when it analyses the packets, and any RTCP Sender Reports from the target device (and indeed several different target types have been tried) also report very large inter arrival jitter numbers at this point! It’s the RTCP side of things that are more of interest here, as trying to get accurate results of our downstream jitter by capturing the returned RTCP packets. I believe that all the times we see this, there is however a Marker bit present!
 
So I guess the question is whether this is expected behaviour, and if not any ideas?
 
No.     Time        Source                Destination           Protocol Info
      1 0.000000    gmtpbx02.redmatter.com sil1.magrathea.net    SIP/SDP  Request: INVITEsip:441277849884@sipipgw.magrathea.net, with session description
      2 0.001595    sil1.magrathea.net    gmtpbx02.redmatter.com SIP      Status: 100 Giving a try
      3 1.103160    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=0, Time=0
      4 1.124816    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=1, Time=160
      5 1.142758    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=2, Time=320
      6 1.163702    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=3, Time=480
      7 1.184239    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=4, Time=640
      8 1.203259    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=5, Time=800
      9 1.223456    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=6, Time=960
     10 1.243953    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=7, Time=1120
     11 1.264504    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=8, Time=1280
     12 1.284839    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=9, Time=1440
     13 1.304590    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=10, Time=1600
     14 1.323589    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=11, Time=1760
     15 1.344672    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=12, Time=1920
     16 1.359227    sil1.magrathea.net    gmtpbx02.redmatter.com SIP/SDP  Status: 183 Session Progress, with session description
     17 1.364522    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=13, Time=2080
     18 1.377484    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53974, Time=160, Mark
     19 1.383466    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=14, Time=2240
     20 1.397476    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53975, Time=320
     21 1.403953    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=15, Time=2400
     22 1.417484    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53976, Time=480
     23 1.423616    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=16, Time=2560
     24 1.437474    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53977, Time=640
     25 1.444930    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=17, Time=2720
     26 1.457475    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53978, Time=800
     27 1.463341    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=18, Time=2880
     28 1.477473    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53979, Time=960
     29 1.484235    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=19, Time=3040
     30 1.497483    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53980, Time=1120
     31 1.503415    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=20, Time=3200
     32 1.517474    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53981, Time=1280
     33 1.523541    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=21, Time=3360
     34 1.537472    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53982, Time=1440
     35 1.543428    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=22, Time=3520
     36 1.557567    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53983, Time=1600
     37 1.563656    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=23, Time=3680
     38 1.577496    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53984, Time=130238272, Mark
     39 1.584747    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=24, Time=3840
     40 1.597474    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53985, Time=130238432
     41 1.603871    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=25, Time=4000
     42 1.617465    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53986, Time=130238432
     43 1.624224    lon-avon-four.magrathea.net gmtpbx02.redmatter.com RTP      PT=ITU-T G.711 PCMU, SSRC=0x216DE2D9, Seq=26, Time=4160
     44 1.637466    gmtpbx02.redmatter.com lon-avon-four.magrathea.net RTP      PT=ITU-T G.711 PCMU, SSRC=0x1855F3A7, Seq=53987, Time=130238592
 
Many thanks,
Neil
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